What use of `inst` produced `Nothing`? Sam
On Tue, Sep 29, 2015 at 3:46 PM, Matthias Felleisen <[email protected]> wrote: > > On Sep 29, 2015, at 3:25 PM, Sam Tobin-Hochstadt <[email protected]> wrote: > >> I think something problematic is happening with type inference here, >> and better types could be picked. Right now, Typed Racket is doing >> this: >> >> (compose (λ (x) x) (inst (λ #:forall (a) ({x : a}) x) Nothing)) >> >> when it should probably do >> >> (compose (λ (x) x) (inst (λ #:forall (a) ({x : a}) x) Any)) >> >> However, using polymorphic arguments (such as your second function) >> to polymorphic functions (such as `compose`) in general won't produce >> the results you want, and I recommend writing the instantiation you >> want explicitly. > > > > Well yes, that's where I started with inst. The Nothing told me I was on the > wrong track with inst. > > What you might be saying is 'use inst for compose'. > > -- Matthias > > > > > >> >> Sam >> >> On Tue, Sep 29, 2015 at 2:33 PM, Matthias Felleisen >> <[email protected]> wrote: >>> >>> Why does this >>> >>>> (compose (λ (x) x) (λ #:forall (a) ({x : a}) x)) >>> >>> have this type: >>> >>>> - : (-> Nothing Any) >>> >>> Thanks -- Matthias >>> >>> >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "Racket Developers" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >>> email to [email protected]. >>> To post to this group, send email to [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/racket-dev/7E7C582D-7066-4073-AAFD-9B6CA99F1F1E%40ccs.neu.edu. >>> For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Racket Developers" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-dev/CAK%3DHD%2BYzanSwPXAG_kE1V7YCJKpYJ8PNEF0ZdZ6eHvy2VNyRaA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
